GSync compatibility - another monitor lottery?

[Vexr]

I've been looking at the Samsung C34F791 (34" Ultrawide 100Hz FreeSync), and the biggest deal for me right now is GSync compatibility.

The messages are mixed regarding this particular panel and it's making me wonder if there's a bit of a lottery going on.

One site reviewing it says it works partially with GSync, in that it will lose display loading up a full screen game with FreeSync enabled, but FreeSync could be enabled once within a game and work fine (or on borderless windowed I assume).

On that GSync compatibility spreadsheet doing the rounds, one user say it works 100% no issue. Another says it works on FreeSync standard mode only (80Hz - 100Hz, aka pretty much useless), and even references someone else saying it works on ultimate mode only (48Hz - 100Hz), but not standard mode - possibly they got that the wrong way round.

Also of note is the site that reviewed the C34F791 and highlighted a GSync compatibility issue also identified the Samsung C34J791 as working without issue with GSync, even though it's the same monitor but with Thunderbolt.

So is GSync compatibility a lottery, like whether or not you get a monitor with intolerable back light bleed / dead pixels etc, or isn't it?

 

[Vexr]

I have this monitor and can confirm the losing display when loading a fullscreen game, it's easily fixed with a quick alt tab.

I use ultimate engine whilst capping my frame rate at 95 with afterburner. I've only really played BF5 and it all seems to be working OK, on the load screens I notice a flickering of the image but I can't recall seeing it in game

Very interesting you describe the exact same thing as the review site, but it's not mentioned on the GSync compatibility spreadsheet. I'm sure I could live with that issue if that's all it is.

I note AMD themselves don't show the C34F791 under their FreeSync supported monitors, but do with the C34J79X (which did get a clean bill of health for GSync):

https://www.amd.com/en/products/freesync-monitors

Makes me wonder if FreeSync on the former is just a tad glitchy even with AMD cards, and so problems have rolled over to / been exacerbated on NVidia cards.

How are frame rates under 48 fps on the C34F791 if you don't mind me asking? Is there some sort of low frame rate compensation / doubling of Hz back in to its FreeSync range?

 

[Vexr]

I couldn't say if I'm honest.

I had lowered the settings to get a constant 95fps before trying freesync and haven't changed them since enabling it.

I can try it with the settings cranked up for you next time I have a game, hopefully over the weekend

I'm using a 1080ti btw

That would be awesome if you could. I've seen this review where they say it has LFC but "flickers like crazy between 45-53 fps", though that was with an R9 290 and it sounds like FreeSync has problems on this monitor with AMD cards before Vega. Doesn't bode too well for GSync compatibility though, which I'd expect to be weaker than with any AMD card.

 

[Vexr]

Seems like it at the moment as information, particularly with monitors that pre-date the update, can be problematic to find. With new monitors reviews and user feedback give more of a clear indication.

No amount of info. reduces the chance of being unlucky and getting a monitor with excessive glow, bleed and dead pixels so its not the same thing.

Its a lack of information rather than the curse of the computer gods that's the issue.

Hopefully. If GSync-compatibility is indeed consistent across all monitors of a certain model, I'd say so. Though going by the compatibility spreadsheet vs what this review found, it looks like mileage may vary. Either that or it calls into question the validity of the spreadsheet, in which case misinformation is a problem.

 

[Vexr]

After seeing some more user testimony that the Samsung C34F791 has serious issues with GSync and managing to find a very decent deal on the C34J791, I've pulled the trigger on the latter. I was certainly swayed by this too:

https://www.eurogamer.net/articles/...esync-monitors-for-nvidia-graphics-cards-7044

Best ultra-wide FreeSync monitor: Samsung LC34J791

This Samsung VA-panel monitor boasts excellent contrast, flawless 48-100Hz FreeSync support on Nvidia graphics cards and very low input lag of 6ms. That's a big improvement over the 23ms of input lag reported on its predecessor, the CF791, which also exhibited flickering with Nvidia graphics cards. The 3440 x 1440 resolution is impressive too, with enough detail to justify the 34-inch span but not enough to require an incredibly high-end PC. Finally, the C34J791 also includes Thunderbolt 3 USB-C, so you can connect a laptop to the monitor while charging it with a single cable. All in all, a convincing modern ultra-wide, and one of the few we've seen to play nicely with Nvidia graphics cards.

I currently have no use for Thunderbolt whatsoever, but flawless Freesync on an NVidia card I certainly do Just hope the switch from IPS to VA isn't going to give me cause for regret.

Cheers for the offer to test the C34F791 @Dwaindibbly, but shouldn't be necessary now (at least not in my case).

 

[Vexr]

Make sure you got Windows 10 as otherwise NVIDIA drivers won't support it!

Windows 10 has long since been installed. I've already felt the benefits of DX12 - surprised any gamer wouldn't be on Win10

No worries, I didn't get time to test this weekend so I'm glad you found a decent deal for what seems to be the better of the two

I dug too deep online and since seen one person say the C34J791 has flickering issues on GSync. I'll found out soon enough for myself as it's en-route now.

 

[Vexr]

Annnd the C34J791 flickers like crazy on my 1070 Ti with ultimate mode Freesync. 'Flawless GSync compatibility' my arse.

There's a thread on reddit that seems to confirm my suspicion about panel lotteries for GSync:

https://www.reddit.com/r/ultrawidemasterrace/comments/an054d/samsung_cj791_or_cf791/

The flickering seems to be some kind of build lottery, I have it on GSYNC compatible and ultimate engine and I dont have any flicker.

Looks like I get another roll of the dice though as the monitor has an unrelated physical defect, so it's getting exchanged. Not feeling too hopeful though as no doubt their stock is all from the same batch.

 

[Vexr]

I'll hope not @LadFromWales - though sounds like another thing to consider. I'm thinking the monitor might be faulty as now turning on FreeSync (standard and ultimate) causes the display to dim, even with GSync disabled on the PC. Enabling GSync, the Hz reported in the screen's OSD is usually miles off in game FPS and fluctuating enormously.

 

[Vexr]

@Deus_rsf that sounds consistent with my experience, though as I later discovered it was borderless windowed mode that caused a lot of my FreeSync woes, which tended to disappear on exclusive full screen mode. In some exclusive full screen games LFC would be good enough that, other than a solitary flicker when going past 48 fps, it'd be fine.

Unfortunately there are a lot of games that are borderless full screen only. In the end I chose to downgrade my GPU and wait it out until NAVI arrives. Maybe the issue was only with my 1070 Ti being an unlucky card or something. There's a sizeable minority of folks who've had similar problems with borderless fullscreen GSync even on full GSync monitors in recent times.

That said, it'll be interesting to see if what happened with my card is happening with other Nvidia cards on this monitor.

 

[Vexr]

Edit : haha, thanks to the pendulum demo I actually understood where the problem is coming from ! It's the way the screen handles backlighting !
Even in the ultimate engine range without triggering LFC, 50 Hz for example is much brighter than 100 Hz ! So when it goes to 40 FPS it goes to 80Hz, which is brighter than 50 Hz !
It's basically just the brightness of the monitor that is not properly set to follow the frequency precisely ! If it were, there wouldn't be any problems !

I noticed something similar, though mainly when trying either Samsung Magic Upscale or Game mode, can't remember which. Depending on what's happening on-screen the brightness would change and look similar to flickering. It was essentially unplayable for me so I made sure to keep both turned off. Maybe that transitional FreeSync flicker I notice at 48 fps is also the brightness switching.

PITA monitor really to figure out what's what, but I agree that when it's happily in its optimal FreeSync range it's top notch even with an Nvidia card*.

*But not in borderless full screen for me.